The present invention relates to improvements in skives used, for example, for stripping a copy sheet from a hot fuser roller in electrographic apparatus.
Skives comprising elongate fingers have been used for stripping sheet-like members from rollers in apparatus of various types. More specifically, skives have been used for deflecting copy sheets from hot fuser rollers in electrographic apparatus. The fuser rollers in such apparatus commonly have a soft, flexible outer surface that is flexed as the copy sheet passes through the nip between a fuser roller and a back-up roller or between two such fuser rollers. This soft suface can be damaged by the skive fingers. Damage to the fuser roller can occur, for example, if the sheet leaving the nip between the rollers causes the skive finger to deflect in a direction which urges the tip end of the skive finger into the soft surface of the fuser roller, thereby gouging the roller surface.
Various attempts have been made to avoid the problem of a skive gouging a soft fuser roll. For example, in U.S. Pat. No. 4,336,992, issued on June 29, 1982 in the names of Szlucha et al, skive fingers are provided which are sufficiently flexible so that they can be deflected entirely out of contact with the fuser roller. The fingers can rotate 360 degrees and return to their operating position.
In other known skiving apparatus weights or springs are used to urge the tip end of the skive or sheet stripper into engagement with a rotating roller. Apparatus of this type is disclosed in U.S. Pat. Nos. 3,885,786 and 3,992,000.
The gouging problem results in expensive repair or replacement of the fuser roller and the skive itself. In addition, some prior skives are complex in construction and thus expensive to manufacture. Also, some known skives require accurate adjustment of weights, springs or other elements during assembly, or in order to maintain the required relationship between the skive and fuser roller. Accordingly, there is a need for an improved skive which will not gouge a fuser roller, and which is inexpensive, easy to install and simple to replace.
A skive with an anti-gouge stiffener is disclosed in my copending U.S. patent application Ser. No. 947,074, filed Dec. 29, 1986. That skive comprises a flexible finger and an anti-gouge stiffener that project from a base. The skive is supported from a bar so that the finger is flexed and has its end spaced from the base in contact with a roller for stripping a sheet from the roller. The anti-gouge stiffener has an end in contact with an intermediate portion of the finger to stiffen the finger and allow it to flex upwardly, but prevent it from flexing in the opposite direction and gouging the roller. A sheet deflected from the roller is guided by the stiffener along a sheet path. However, a sheet stripped from the roller by the finger can strike the end of the stiffener adjacent the finger, or a recess in the stiffener where the skive is mounted on the bar. This stubbing of the sheet can damage the sheet and interfere with its smooth movement along its path away from the roller. Accordingly, it is desirable to remove potential stubpoints from a skive such as disclosed in my copending application.